先附上比较简单的判断方法:
def func(num):
try:
float(num)
return True
except ValueError:
return False
while 1:
print(func(input("请输入数字:")))
闲来无事,绕了半天,写了个最不容易懂的判断方法。
# 判断一个字符串是否是整数或小数
def func(num):
if num:
# 正整数
if num.isdigit():
return True
# 负整数
elif num[0] == '-' and num.count('-') == 1 and len(num) > 1 and '.' not in num:
num = num[1:]
if num.isdigit():
return True
else:
return False
# 正小数
elif '.' in num and num[0] != '.' and num[len(num) - 1] != '.' and num.count('.') == 1 and num[
num.find('.') - 1] in "0123456789" and len(num) > 1 and '-' not in num:
index = num.index('.')
for i in range(len(num)):
if num[i] not in "0123456789" and i != index:
return False
else:
return True
# 负小数
elif '.' in num and num[0] != '.' and num[len(num) - 1] != '.' and num.count('.') == 1 and num[
num.find('.') - 1] in "0123456789" and num[0] == '-' and num.count('-') == 1 and len(num) > 2:
num = num[1:]
index = num.index('.')
for i in range(len(num)):
if num[i] not in "0123456789" and i != index:
return False
else:
return True
else:
return False
else:
return False
while 1:
print(func(input("请输入数字:")))
也在最后附上使用正则表达式判断的方式
#引用re正则模块
import re
num = input("Please input the number:")
#调用正则
value = re.compile(r'^[-+]?[0-9]+\.[0-9]+$')
result = value.match(num)
if result:
return True
else:
return False